SWARUtil Class — netty Architecture

Source Code

common/src/main/java/io/netty/util/internal/SWARUtil.java lines 21–176

public final class SWARUtil {

    /**
     * Compiles given byte into a long pattern suitable for SWAR operations.
     */
    public static long compilePattern(byte byteToFind) {
        return (byteToFind & 0xFFL) * 0x101010101010101L;
    }

    /**
     * Applies a compiled pattern to given word.
     * Returns a word where each byte that matches the pattern has the highest bit set.
     *
     * @param word    the word to apply the pattern to
     * @param pattern the pattern to apply
     * @return a word where each byte that matches the pattern has the highest bit set
     */
    public static long applyPattern(final long word, final long pattern) {
        long input = word ^ pattern;
        long tmp = (input & 0x7F7F7F7F7F7F7F7FL) + 0x7F7F7F7F7F7F7F7FL;
        return ~(tmp | input | 0x7F7F7F7F7F7F7F7FL);
    }

    /**
     * Returns the index of the first occurrence of byte that specificied in the pattern.
     * If no pattern is found, returns 8.
     *
     * @param word     the return value of {@link #applyPattern(long, long)}
     * @param isBigEndian if true, if given word is big endian
     *                 if false, if given word is little endian
     * @return the index of the first occurrence of the specified pattern in the specified word.
     * If no pattern is found, returns 8.
     */
    public static int getIndex(final long word, final boolean isBigEndian) {
        final int zeros = isBigEndian? Long.numberOfLeadingZeros(word) : Long.numberOfTrailingZeros(word);
        return zeros >>> 3;
    }

    /**
     * Returns a word where each ASCII uppercase byte has the highest bit set.
     */
    private static long applyUpperCasePattern(final long word) {
        // Inspired by https://github.com/facebook/folly/blob/add4049dd6c2371eac05b92b6fd120fd6dd74df5/folly/String.cpp
        long rotated = word & 0x7F7F7F7F7F7F7F7FL;
        rotated += 0x2525252525252525L;
        rotated &= 0x7F7F7F7F7F7F7F7FL;
        rotated += 0x1A1A1A1A1A1A1A1AL;
        rotated &= ~word;
        rotated &= 0x8080808080808080L;
        return rotated;
    }

    /**
     * Returns a word where each ASCII uppercase byte has the highest bit set.
     */
    private static int applyUpperCasePattern(final int word) {
        int rotated = word & 0x7F7F7F7F;
        rotated += 0x25252525;
        rotated &= 0x7F7F7F7F;
        rotated += 0x1A1A1A1A;
        rotated &= ~word;
        rotated &= 0x80808080;
        return rotated;
    }

    /**
     * Returns a word where each ASCII lowercase byte has the highest bit set.
     */
    private static long applyLowerCasePattern(final long word) {
        long rotated = word & 0x7F7F7F7F7F7F7F7FL;
        rotated += 0x0505050505050505L;
        rotated &= 0x7F7F7F7F7F7F7F7FL;
        rotated += 0x1A1A1A1A1A1A1A1AL;
        rotated &= ~word;
        rotated &= 0x8080808080808080L;
        return rotated;
    }

    /**
     * Returns a word where each lowercase ASCII byte has the highest bit set.
     */